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[Poll]
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Earth Basics
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| The Earth is round, and gravitational attraction is in force |
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| The Earth is flat. You can fall off the edge. |
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| The Earth does not rotate on an axis. It stands still |
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| The Earth rotates around the Sun |
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| Science is a tool of Satan, as is education in general |
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| Science is neither moral nor immoral. |
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Total Votes : 105
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(last vote on : 8/14/2008 10:02:09 PM)
(Poll will run till: -- )
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RE: Earth Basics - 3/29/2008 1:25:10 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
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quote:
ORIGINAL: DanJames
Are you two married or something? I could swear you two are arguing, but not really because you're not disagreeing. Objects can appear to "move" faster than light if they're traveling along with and parallel to the plane of spacial expansion when the point of reference is along the opposite side of the plane of spacial expansion (moving in the opposite direction).
I guess the problem here is defining movement. An object maybe moving relative to another object in a distance but it may not be moving (as fast) relative to an object closer to it (and the reverse maybe true as well), even if the movement is attributed to spacial expansion. Think of it this way. We are moving relative to the moon but we may not be moving relative to a car we are standing by. If the space between two objects increases, they are moving relative to each other but they may not be moving relative to local objects. C as a limitation on the speed that an object can travel applies on a local scale, but on a global scale objects can "move" faster than C. Movement is a relative word, an object moves relative some other object(s). An object may move relative to one point of reference and not move relative to another.
< Message edited by Bettawrekonize -- 3/29/2008 1:36:31 PM >
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RE: Earth Basics - 3/29/2008 1:45:10 PM
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DanJames
Posts: 679
Joined: 12/13/2007
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I see, good way of putting it. You're just saying that things could "move" faster than the speed of light depending on how you define movement. You are not saying that this is a good argument for the universe going around the earth, just that it gives rise to the possibility that a universal speed limit is not a crushing argument against it.
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RE: Earth Basics - 3/29/2008 1:58:40 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
Status: offline
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quote:
ORIGINAL: DanJames
I see, good way of putting it. You're just saying that things could "move" faster than the speed of light depending on how you define movement. You are not saying that this is a good argument for the universe going around the earth, just that it gives rise to the possibility that a universal speed limit is not a crushing argument against it.
Exactly.
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RE: Earth Basics - 3/29/2008 4:39:04 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
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quote:
ORIGINAL: phosadaud
Guess we're going to have to agree to disagree on that one.  Unless you can come up with another way for objects to revolve around other objects that change how movement is defined, I still think you're argument is apples and oranges.
My argument does not mix apples and oranges. You are now attempting another argument against everything revolving around the earth, but I never argued that everything is revolving around earth to begin with. I am simply arguing that an upper limit on speed is not a good argument against everything revolving around earth and you have not refuted that.
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The fact is objects do not move faster than the speed of light
With respect to each other they do.
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and there is simply no way that an object revolving around another object can be related to spacial expansion. Again, apples and oranges.
Again, you are bringing up another argument altogether.
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Could someday science discover a way for planets and celestial bodies to physically move faster than the speed of light? I suppose anything is possible, but that could be said of anything which is why it's not an argument. At least not a scientific one.  So, unless you want to change the laws of physics, it's silly to argue that:
I am not changing the laws of physics. Some galaxies (which contain objects) are already moving away from each other (with respect to each other) faster than the speed of light. You may attribute this to spacial expansion, but the fact is that the distance between them is changing faster than the speed of light which means they are moving with respect to each other faster than the speed of light. Their relative positions can change faster than the speed of light.
One possibility (and I am not arguing this to be true) is that maybe space is spinning around very fast. When the moon revolves around the earth, the revolution itself causes it to move further and further away from the earth (centrifugal force). Gravity balances this out and the moon neither falls to the earth or drifts away (too quickly). When earth goes around the sun, the revolution causes it to move further and further away from the sun (this is countered by gravity). If the universe is expanding and space is expanding (though I think that spacial expansion has its own problems and likewise this theory would have similar problems), if space and the universe itself rotate perhaps this spacial rotation is what pushes everything (including space itself) away from the center (causing space to expand). If space can expand, why can't it rotate, and the fact that it's expanding could be considered evidence of its rotation (kind of like centrifugal force).
< Message edited by Bettawrekonize -- 3/29/2008 4:58:36 PM >
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RE: Earth Basics - 3/29/2008 5:56:32 PM
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phosadaud
Posts: 11092
Joined: 9/19/2005
From: Washington State
Status: offline
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quote:
ORIGINAL: Bettawrekonize
quote:
ORIGINAL: phosadaud
Guess we're going to have to agree to disagree on that one. Unless you can come up with another way for objects to revolve around other objects that change how movement is defined, I still think you're argument is apples and oranges.
My argument does not mix apples and oranges. You are now attempting another argument against everything revolving around the earth, but I never argued that everything is revolving around earth to begin with. I am simply arguing that an upper limit on speed is not a good argument against everything revolving around earth and you have not refuted that.
Science would disagree with you. Re-read what I posted.
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The fact is objects do not move faster than the speed of light
With respect to each other they do.
But the objects speed does not. An object moving away from another object doesn't speed up just because it's moving away from another object. The spatial expansion may be increasing faster than the speed of light, but an objects speed does not change because it's moving away from something.
You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast. Now, you turn around and walk 4mph towards me and I continue walking away. My speed is still the same but now there is no spatial expansion.
Again, apples and oranges.
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and there is simply no way that an object revolving around another object can be related to spacial expansion. Again, apples and oranges.
Again, you are bringing up another argument altogether.
No, I'm getting back to the initial argument which is you claiming that spatial expansion somehow hurts the argument against the earth being the center of the solar system. The problem is your argument is apples and oranges.
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Could someday science discover a way for planets and celestial bodies to physically move faster than the speed of light? I suppose anything is possible, but that could be said of anything which is why it's not an argument. At least not a scientific one. So, unless you want to change the laws of physics, it's silly to argue that:
I am not changing the laws of physics. Some galaxies (which contain objects) are already moving away from each other (with respect to each other) faster than the speed of light. You may attribute this to spacial expansion, but the fact is that the distance between them is changing faster than the speed of light which means they are moving with respect to each other faster than the speed of light. Their relative positions can change faster than the speed of light.
Which is spatial expansion and I gave an illustration above to show why spatial expansion is not contrary to the relativity.
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One possibility (and I am not arguing this to be true) is that maybe space is spinning around very fast. When the moon revolves around the earth, the revolution itself causes it to move further and further away from the earth (centrifugal force). Gravity balances this out and the moon neither falls to the earth or drifts away (too quickly). When earth goes around the sun, the revolution causes it to move further and further away from the sun (this is countered by gravity). If the universe is expanding and space is expanding (though I think that spacial expansion has its own problems and likewise this theory would have similar problems), if space and the universe itself rotate perhaps this spacial rotation is what pushes everything (including space itself) away from the center (causing space to expand). If space can expand, why can't it rotate, and the fact that it's expanding could be considered evidence of its rotation (kind of like centrifugal force).
It can do whatever it wants to, but the reason spatial expansion can be faster than the speed of light is because of basic laws of physics/mathematics. I am unaware of any law in physics that would result in revolutions allowing objects to move faster than the speed of light while revolving around other objects.
_____________________________
~Kristin~
Classified Ads: "Government employer looking for candidates. Criminal background required."
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RE: Earth Basics - 3/29/2008 6:23:10 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
Status: offline
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quote:
ORIGINAL: phosadaud
Science would disagree with you. Re-read what I posted.
Correction, "you" would disagree with me and you are not the ultimate authority on science.
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But the objects speed does not. An object moving away from another object doesn't speed up just because it's moving away from another object.
Its speed with respect to the other object may.
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The spatial expansion may be increasing faster than the speed of light, but an objects speed does not change because it's moving away from something.
It's distance (and hence position) relative to the other object changes.
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You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast. Now, you turn around and walk 4mph towards me and I continue walking away. My speed is still the same but now there is no spatial expansion.
In this situation neither of us are moving relative to one another (though we maybe moving relative to other objects).
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Again, apples and oranges.
Nope.
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No, I'm getting back to the initial argument which is you claiming that spatial expansion somehow hurts the argument against the earth being the center of the solar system.
It hurts the argument that an upper limit on speed is an argument against the earth being the center of the universe. I am not arguing the earth is the center of the universe.
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The problem is your argument is apples and oranges.
No, it does not.
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Which is spatial expansion and I gave an illustration above to show why spatial expansion is not contrary to the relativity.
I never said it was.
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It can do whatever it wants to, but the reason spatial expansion can be faster than the speed of light is because of basic laws of physics/mathematics.
We derive our understanding of the laws of physics based on our perceived observations and interpretations that spacial expansion is faster than the speed of light (and we may use other observations as well). We don't derive spacial expansion (and other observations) based on our perception of the laws of physics. Our understanding of the laws of physics is derived from our observations. Our observations are not derived from our understanding of the laws of physics. If our observations supports (or could support) a rotating universe, then we deduce that the laws of physics (could) allow for this.
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I am unaware of any law in physics that would result in revolutions allowing objects to move faster than the speed of light while revolving around other objects.
My point is that C as an upper limit to speed is not an argument against the universe revolving around the earth. Secondly, it's not a matter of what laws of physics you are or aren't aware of. We deduce the laws of physics based on what we observe, if what we observe supports spacial expansion or if it supports spacial rotation, then we deduce that the laws of physics allow for this. I am not interested in what laws of physics you are "aware" of, as if your awareness of the laws of physics is the ultimate authority on what the laws are. I am interested in what can be deduced based on our observations.
< Message edited by Bettawrekonize -- 3/29/2008 6:40:35 PM >
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RE: Earth Basics - 3/29/2008 6:46:19 PM
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phosadaud
Posts: 11092
Joined: 9/19/2005
From: Washington State
Status: offline
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quote:
ORIGINAL: Bettawrekonize
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But the objects speed does not. An object moving away from another object doesn't speed up just because it's moving away from another object.
Its speed with respect to the other object may.
The speed of spacial expansion is not the same thing as the speed of an object. I don't know how else to explain it. Galaxies receding is not the measurement of the speed those galaxies are moving - it's the speed of the expansion of space between them.
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The spatial expansion may be increasing faster than the speed of light, but an objects speed does not change because it's moving away from something.
It's distance (and hence position) relative to the other object changes.
Correct, but the object isn't moving any faster just because the distance between 2 objects is increasing.
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You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast. Now, you turn around and walk 4mph towards me and I continue walking away. My speed is still the same but now there is no spatial expansion.
In this situation neither of us are moving relative to one another (though we maybe moving relative to other objects).
I think you misread my illustration. The point of the illustration is that we are moving relative to one another and that the speed of the spacial expansion between us changes even if our speeds remain constant. Granted this is oversimplified as we can only head in one direction, but the idea is the same.
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No, I'm getting back to the initial argument which is you claiming that spatial expansion somehow hurts the argument against the earth being the center of the solar system.
It hurts the argument that an upper limit on speed is an argument against the earth being the center of the universe. I am not arguing the earth is the center of the universe.
Again, it would only hurt the argument IF there was evidence that an object's speed could surpass the speed of light. The speed of spatial expansion does not disprove this because no objects are moving faster than the speed of light. I don't know how else to describe it. The spatial expanse between our sun and another solar system's sun may be moving apart faster than the speed of light, but that does not mean our sun or the other sun is moving faster than the speed of light. It's apples and oranges.
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Which is spatial expansion and I gave an illustration above to show why spatial expansion is not contrary to the relativity.
I never said it was.
But, relativity would have to be chucked out the window in order for the earth to be the center of the universe. If your example does not refute relativity, it is not proof that relativity is not a strong argument against the earth being the center of the universe.
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It can do whatever it wants to, but the reason spatial expansion can be faster than the speed of light is because of basic laws of physics/mathematics.
We derive our understanding of the laws of physics based on our perceived observations and interpretations that spacial expansion is faster than the speed of light. We don't derive spacial expansion based on our perception of the laws of physics.
The 2 work hand in hand. That's why discoveries that change our perceptions of the laws of physics are so huge.
_____________________________
~Kristin~
Classified Ads: "Government employer looking for candidates. Criminal background required."
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RE: Earth Basics - 3/29/2008 6:56:08 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
Status: offline
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quote:
ORIGINAL: phosadaud
The speed of spacial expansion is not the same thing as the speed of an object. I don't know how else to explain it. Galaxies receding is not the measurement of the speed those galaxies are moving - it's the speed of the expansion of space between them.
It's the speed of the objects relative to one another.
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Correct, but the object isn't moving any faster just because the distance between 2 objects is increasing.
It's moving relative to the other object.
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I think you misread my illustration. The point of the illustration is that we are moving relative to one another and that the speed of the spacial expansion between us changes even if our speeds remain constant. Granted this is oversimplified as we can only head in one direction, but the idea is the same.
If the distance between us changes, then we are moving relative to one another. If the distance between us stays the same, then we may not be moving relative to one another.
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Again, it would only hurt the argument IF there was evidence that an object's speed could surpass the speed of light.
It could, relative to other objects.
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The speed of spatial expansion does not disprove this because no objects are moving faster than the speed of light.
They are, relative to other objects.
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The spatial expanse between our sun and another solar system's sun may be moving apart faster than the speed of light, but that does not mean our sun or the other sun is moving faster than the speed of light. It's apples and oranges.
They're moving relative to each other. It's not apples and oranges. Their distance and hence their position is changing relative to each other so they are moving relative to each other.
Also: How do you know that the stars aren't simply moving apart from one another. How do you know that space is expanding? If space can expand, why can't space rotate? Maybe space itself is rotating and this rotation of space is what's causing it to expand (kinda like centrifugal force). If space is not bound by the speed of light, then perhaps space itself can rotate faster than the speed of light. If spacial expansion can cause the objects to recede faster than the speed of light, why can't spacial rotation cause them to revolve faster (in which case you would argue, "the objects aren't moving, it's spacial rotation")?
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But, relativity would have to be chucked out the window in order for the earth to be the center of the universe. If your example does not refute relativity, it is not proof that relativity is not a strong argument against the earth being the center of the universe.
Upper limits on the speed of light apply to local objects.
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The 2 work hand in hand. That's why discoveries that change our perceptions of the laws of physics are so huge.
Yep.
< Message edited by Bettawrekonize -- 3/29/2008 7:11:31 PM >
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RE: Earth Basics - 3/29/2008 7:22:49 PM
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phosadaud
Posts: 11092
Joined: 9/19/2005
From: Washington State
Status: offline
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quote:
ORIGINAL: Bettawrekonize
quote:
ORIGINAL: phosadaud
The speed of spacial expansion is not the same thing as the speed of an object. I don't know how else to explain it. Galaxies receding is not the measurement of the speed those galaxies are moving - it's the speed of the expansion of space between them.
It's the speed of the objects relative to one another.
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Correct, but the object isn't moving any faster just because the distance between 2 objects is increasing.
It's moving relative to the other object.
Oy. Let me explain this another way: Two objects are moving away from each other at a speed just under the speed of sound. Relative to each other, they recede at a rate that exceeds the speed of sound, but the speed of sound is never breached and there is not sonic boom because the objects never supercede the speed of sound.
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I think you misread my illustration. The point of the illustration is that we are moving relative to one another and that the speed of the spacial expansion between us changes even if our speeds remain constant. Granted this is oversimplified as we can only head in one direction, but the idea is the same.
If the distance between us changes, then we are moving relative to one another. If the distance between us stays the same, then we may not be moving relative to one another.
Oy again. Please reread my illustration, especially this part:
"You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast."
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The spatial expanse between our sun and another solar system's sun may be moving apart faster than the speed of light, but that does not mean our sun or the other sun is moving faster than the speed of light. It's apples and oranges.
They're moving relative to each other. It's not apples and oranges. Their distance and hence their position is changing relative to each other so they are moving relative to each other.
It doesn't matter what they are doing relative to another object. If that was the definition of the speed of light, that would mean that galaxies are moving billions of different speeds at the same time because they are moving relative to billions of other objects at the same time.
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Also: How do you know that the stars aren't simply moving apart from one another. How do you know that space is expanding? If space can expand, why can't space rotate? Maybe space itself is rotating and this rotation of space is what's causing it to expand (kinda like centrifugal force). If space is not bound by the speed of light, then perhaps space itself can rotate faster than the speed of light.
I never said it couldn't rotate. It could be doing jumping jacks for all I care. That doesn't change the fact that objects cannot go faster than the speed of light something that would be required if the earth was the center of the universe and everything revolved around it.
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But, relativity would have to be chucked out the window in order for the earth to be the center of the universe. If your example does not refute relativity, it is not proof that relativity is not a strong argument against the earth being the center of the universe.
Upper limits on the speed of light apply to local objects.
Does this help it make anymore sense?
According to Hubble's Law, two galaxies that are a distance D apart are moving away from each other at a speed HD, where H is Hubble's constant. So this interpretation of Hubble's Law implies that two galaxies separated by a distance greater than c/H must be moving away from each other faster than the speed of light. Actually, the modern viewpoint describes this situation differently: general relativity takes the galaxies as being at rest relative to one another, while the space between them is expanding. In that sense, the galaxies are not moving away from each other faster than the speed of light; they are not moving away from each other at all! This change of viewpoint is not arbitrary; rather, it's in accord with the different but very fruitful view of the universe that general relativity provides. So the distance between two objects can be increasing faster than light because of the expansion of the universe, but this does not mean, in fact, that their relative speed is faster than light.As was mentioned above, in special relativity it is possible for two objects to be moving apart by speeds up to twice the speed of light as measured by an observer in a third frame of reference. In general relativity even this limit can be surpassed, but it will not then be possible to observe both objects at the same time. Again, this is not real faster than light travel; it will not help anyone to travel across the galaxy faster than light.
_____________________________
~Kristin~
Classified Ads: "Government employer looking for candidates. Criminal background required."
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RE: Earth Basics - 3/29/2008 7:39:58 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
Status: offline
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quote:
ORIGINAL: phosadaud
Oy. Let me explain this another way: Two objects are moving away from each other at a speed just under the speed of sound. Relative to each other, they recede at a rate that exceeds the speed of sound, but the speed of sound is never breached and there is not sonic boom because the objects never supercede the speed of sound.
They are moving faster than the speed of sound relative to each other but there is no sonic boom because, relative to the air that's surrounding them, they aren't moving faster than the speed of sound.
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Oy again. Please reread my illustration, especially this part:
"You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast."
and we are moving away from each other twice as fast relative to each other. Your speed relative to some other object maybe the same though.
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It doesn't matter what they are doing relative to another object. If that was the definition of the speed of light, that would mean that galaxies are moving billions of different speeds at the same time because they are moving relative to billions of other objects at the same time.
Relative to billions of other objects, "galaxies are moving billions of different speeds at the same time because they are moving relative to billions of other objects at the same time."
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I never said it couldn't rotate. It could be doing jumping jacks for all I care. That doesn't change the fact that objects cannot go faster than the speed of light something that would be required if the earth was the center of the universe and everything revolved around it.
Objects can't go faster than the speed of light relative to the light around it. This applies on a local scale.
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According to Hubble's Law, two galaxies that are a distance D apart are moving away from each other at a speed HD, where H is Hubble's constant. So this interpretation of Hubble's Law implies that two galaxies separated by a distance greater than c/H must be moving away from each other faster than the speed of light. Actually, the modern viewpoint describes this situation differently: general relativity takes the galaxies as being at rest relative to one another, while the space between them is expanding. In that sense, the galaxies are not moving away from each other faster than the speed of light; they are not moving away from each other at all!
In that sense this maybe true. In the sense of the change in their distances and hence positions, they are moving relative to each other. It's possible for them to move faster than the speed of light relative to each other in terms of how we observe their relative positions.
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This change of viewpoint is not arbitrary; rather, it's in accord with the different but very fruitful view of the universe that general relativity provides.
Please elaborate.
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So the distance between two objects can be increasing faster than light because of the expansion of the universe, but this does not mean, in fact, that their relative speed is faster than light.As was mentioned above, in special relativity it is possible for two objects to be moving apart by speeds up to twice the speed of light as measured by an observer in a third frame of reference. In general relativity even this limit can be surpassed, but it will not then be possible to observe both objects at the same time. Again, this is not real faster than light travel; it will not help anyone to travel across the galaxy faster than light.
In terms of how we observe objects, its possible for them to move faster than the speed of light.
You left out a lot of important quotes.
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What it comes down to is the fact that velocities in different places cannot be compared directly in general relativity. Notice that the Moon is not overtaking any light in its own locality. The speed of the Moon can only be compared to the speeds of other objects in its own local inertial frame. Indeed, the concept of speed is not a very useful one in general relativity, and this makes it difficult to define what "faster than light" means. Even the statement that "the speed of light is constant" is open to interpretation in general relativity. Einstein himself, on page 76 of his book "Relativity: the Special and the General Theory", wrote that the statement cannot claim unlimited validity. When there is no absolute definition of time and distance it is not so clear how speeds should be determined.
...
In relativity there is no such thing as absolute velocity, only relative velocity
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html#13
Again, C as an upper limit to speed only applies on a local scale. On a global scale, everything is relative to ones frame of reference and things can move (at least in terms of how we observe them) faster than the speed of light (regardless of whether you want to attribute this observed motion to spacial expansion or to them actually moving apart from one another, it doesn't matter). I am interested here in observed speeds, not perceived spacial expansion. Based on observed speeds, it's possible for two objects to move faster than the speed of light. One can attribute this to spacial expansion if s/he likes, but the point is that it's possible to observe an object moving faster than C.
< Message edited by Bettawrekonize -- 3/29/2008 7:54:59 PM >
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RE: Earth Basics - 3/29/2008 10:26:10 PM
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phosadaud
Posts: 11092
Joined: 9/19/2005
From: Washington State
Status: offline
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quote:
ORIGINAL: Bettawrekonize
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ORIGINAL: phosadaud
Oy. Let me explain this another way: Two objects are moving away from each other at a speed just under the speed of sound. Relative to each other, they recede at a rate that exceeds the speed of sound, but the speed of sound is never breached and there is not sonic boom because the objects never supercede the speed of sound.
They are moving faster than the speed of sound relative to each other but there is no sonic boom because, relative to the air that's surrounding them, they aren't moving faster than the speed of sound.
Hence, they are not moving faster than the speed of sound.
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Oy again. Please reread my illustration, especially this part:
"You and I stand together. I walk away from you at 4mph. Now, you begin to walk away from me at 4mph and I continue my walk. My speed is the same, but the spatial distance between us is now expanding twice as fast."
and we are moving away from each other twice as fast relative to each other. Your speed relative to some other object maybe the same though.
And my speed doesn't change. Do you think the courts would let you off on a speeding ticket because your relative to some other car on the road was below the speed limit?
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This change of viewpoint is not arbitrary; rather, it's in accord with the different but very fruitful view of the universe that general relativity provides.
Please elaborate.
That was the author's quote, not mine.
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So the distance between two objects can be increasing faster than light because of the expansion of the universe, but this does not mean, in fact, that their relative speed is faster than light.As was mentioned above, in special relativity it is possible for two objects to be moving apart by speeds up to twice the speed of light as measured by an observer in a third frame of reference. In general relativity even this limit can be surpassed, but it will not then be possible to observe both objects at the same time. Again, this is not real faster than light travel; it will not help anyone to travel across the galaxy faster than light.
In terms of how we observe objects, its possible for them to move faster than the speed of light.
That's not the same thing as the objects actually physically moving faster than the speed of light.
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You left out a lot of important quotes.
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What it comes down to is the fact that velocities in different places cannot be compared directly in general relativity. Notice that the Moon is not overtaking any light in its own locality. The speed of the Moon can only be compared to the speeds of other objects in its own local inertial frame. Indeed, the concept of speed is not a very useful one in general relativity, and this makes it difficult to define what "faster than light" means. Even the statement that "the speed of light is constant" is open to interpretation in general relativity. Einstein himself, on page 76 of his book "Relativity: the Special and the General Theory", wrote that the statement cannot claim unlimited validity. When there is no absolute definition of time and distance it is not so clear how speeds should be determined.
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In relativity there is no such thing as absolute velocity, only relative velocity
Context of the quote, context. Your first quote was discussing whether the moon is traveling faster than the speed of light when you turn around and the moon "in essence" goes around your head.
You'll have to point out where you found the second quote.
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Again, C as an upper limit to speed only applies on a local scale. On a global scale, everything is relative to ones frame of reference and things can move (at least in terms of how we observe them) faster than the speed of light (regardless of whether you want to attribute this observed motion to spacial expansion or to them actually moving apart from one another, it doesn't matter). I am interested here in observed speeds, not perceived spacial expansion. Based on observed speeds, it's possible for two objects to move faster than the speed of light. One can attribute this to spacial expansion if s/he likes, but the point is that it's possible to observe an object moving faster than C.
Science is not based simply on observation. Observation is only one component. I can observe something under the water of my pool and when I reach for it, it's somewhere different because of "refraction". That doesn't mean it's actually somewhere different even though I observe it to be.
The same is true here (although technically one could not observe this). Is an object actually moving faster than the speed of light? No.
So the question becomes this:
In order for the stars and galaxies to revolve around the earth at what we observe them to, they would have to be traveling "relative to the air or space" (if you want to keep on that), well, well faster than the speed of light - not relative to anything else. As a result, it would have to be possible for objects to travel "relative to space" faster than C. There is no evidence that this is possible and the speed of galaxies receding from each other is apples and oranges because they are not traveling faster than the speed of light "relative to space".
_____________________________
~Kristin~
Classified Ads: "Government employer looking for candidates. Criminal background required."
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RE: Earth Basics - 3/29/2008 11:01:54 PM
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Bettawrekonize
Posts: 1400
Joined: 4/17/2005
Status: offline
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ORIGINAL: phosadaud
Hence, they are not moving faster than the speed of sound.
Depends on what you're using as your frame of reference.
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And my speed doesn't change. Do you think the courts would let you off on a speeding ticket because your relative to some other car on the road was below the speed limit?
No, because it's implied that we're basing our speed relative to the ground.
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This change of viewpoint is not arbitrary; rather, it's in accord with the different but very fruitful view of the universe that general relativity provides.
Please elaborate.
That was the author's quote, not mine.
You did say, "The speed of spatial expansion does not disprove this because no objects are moving faster than the speed of light." which suggests you agree with the author on this (unless you are suggesting that galaxies are not receding faster than C).
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That's not the same thing as the objects actually physically moving faster than the speed of light.
In general relativity there is no set point of reference so what you're saying doesn't matter. Physically moving faster than the speed of light with respect to what? If you want to argue with respect to space, how do know space itself is not rotating and making it revolve in the same way it makes it expand? I'm not arguing this to be the case, but if space could expand, why can't it rotate? Perhaps its rotation is what's making it expand (kinda like centrifugal force).
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Your first quote was discussing whether the moon is traveling faster than the speed of light when you turn around and the moon "in essence" goes around your head.
I know, but the point it makes still stands.
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You'll have to point out where you found the second quote.
Same document.
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Science is not based simply on observation. Observation is only one component. I can observe something under the water of my pool and when I reach for it, it's somewhere different because of "refraction". That doesn't mean it's actually somewhere different even though I observe it to be.
From a scientific standpoint, observation is broadly interpreted to mean that which we detect with all our senses, not just our eyes.
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The same is true here (although technically one could not observe this). Is an object actually moving faster than the speed of light? No.
Again, depends on your frame of reference.
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In order for the stars and galaxies to revolve around the earth at what we observe them to, they would have to be traveling "relative to the air or space" (if you want to keep on that), well, well faster than the speed of light - not relative to anything else.
You're the one that brought up the "air or space" when you said, "The speed of spatial expansion does not disprove this because no objects are moving faster than the speed of light." So if there is no "air or space", galaxies are in fact moving faster than the speed of light relative to one another which means that it's possible for two objects to exceed the speed of light relative to one another. If there is "air or space" and it is the air or space that is expanding, then it could be possible that the "air or space" is rotating and hence everything is "revolving" (spacial revolution) with the air or space in much the same way it expands with the air or space. Perhaps the rotation of the universe is what causes this expansion (like centrifugal force).
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As a result, it would have to be possible for objects to travel "relative to space" faster than C.
See above (if recession is not a result of spacial expansion, then they are already moving faster than C. If they are, if space could expand why can't it rotate? Perhaps the expansion is a result of its rotation, kind of like centrifugal force).
< Message edited by Bettawrekonize -- 3/29/2008 11:09:26 PM >
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RE: Earth Basics - 3/29/2008 11:39:14 PM
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phosadaud
Posts: 11092
Joined: 9/19/2005
From: Washington State
Status: offline
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I can see that I'm not being clear and I'm not sure how else to make myself clear. Maybe someone else can explain it in a way that I'm apparently not. In the meantime, I stand by what I have posted and we will just have to agree to disagree.
_____________________________
~Kristin~
Classified Ads: "Government employer looking for candidates. Criminal background required."
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RE: Earth Basics - 3/30/2008 1:58:16 PM
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DanJames
Posts: 679
Joined: 12/13/2007
Status: offline
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ORIGINAL: phosadaud
I can see that I'm not being clear and I'm not sure how else to make myself clear. Maybe someone else can explain it in a way that I'm apparently not. In the meantime, I stand by what I have posted and we will just have to agree to disagree.
I'm not even sure why this argument is still going on. I thought you were both pretty clear. Objects can't go faster than light, but with spacial expansion and two moving reference points they can appear from one reference to be moving faster than the speed of light. They can't orbit around an object faster than light unless space somehow "carries" them around the object faster than light. Seems oversimplified, stupid, and scientifically heretical, but it follows the a=b=c train of thought.
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RE: Earth Basics - 3/30/2008 4:18:00 PM
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Veritas
Posts: 528
Joined: 4/19/2005
Status: offline
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quote:
ORIGINAL: Bettawrekonize
See above (if recession is not a result of spacial expansion, then they are already moving faster than C. If they are, if space could expand why can't it rotate? Perhaps the expansion is a result of its rotation, kind of like centrifugal force).
If you want to say the universe is rotating, you need to specify rotation relative to what stationary frame. Let's ignore that for the moment.
A plane can rotate about a point. A 3-D space would rotate about a line. If the recession were due to rotation, we would observe distant objects receding from a line. Objects along the axis would not be receding. What we observe is objects receding in all directions.
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RE: Earth Basics - 3/31/2008 1:11:31 PM
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DanJames
Posts: 679
Joined: 12/13/2007
Status: offline
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ORIGINAL: Veritas
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ORIGINAL: Bettawrekonize
See above (if recession is not a result of spacial expansion, then they are already moving faster than C. If they are, if space could expand why can't it rotate? Perhaps the expansion is a result of its rotation, kind of like centrifugal force).
If you want to say the universe is rotating, you need to specify rotation relative to what stationary frame. Let's ignore that for the moment.
A plane can rotate about a point. A 3-D space would rotate about a line. If the recession were due to rotation, we would observe distant objects receding from a line. Objects along the axis would not be receding. What we observe is objects receding in all directions.
I think that it was all just a big misunderstanding. Nobody is really suggesting that the universe is rotating around the earth. It was merely suggested that the universal speed limit may not be a valid argument against it.
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